Systems including power trains for actuating, for example, control surfaces on aircraft, and which require geared rotary actuators typically require high capacity overtravel stops. Such stops prevent system components from moving past positions defining the ends of a path of travel as a result of inertial loading within the system. In the usual case, most inertial energy in the system is located at the drive motor in the power drive unit. Consequently, the preferred location for a stop mechanism is remote from the motor so that shafting between the motor and the stops can provide a soft, spring-like action when the stops are engaged. In aircraft, this means that the stop mechanism should be located very close to the geared rotary actuator which in turn is in close proximity to the control surface to be moved. And, as in all aircraft situations, it is desirable that the system be light in weight as well as of small bulk and of minimal complexity to minimize cost and enhance reliability.
The present invention is directed to the provision that a geared rotary actuator incorporating an internal stop mechanism to achieve minimal cost, weight, bulk and complexity.